Apparatus are employed in the field of fitness and therapy that produce vibrations which are transmitted via a contact surface onto the person to be treated or trained. The vibrations may have a positive effect on muscles as well as on bones. An effective stimulation of muscle fibers is possible if the muscle fibers are brought in an oscillating manner from a basic tonus, or muscle tone, into a threshold region with an increased tension. The basic tonus depends on the constitutional tonus and on the pre-tension selected during the treatment. The pre-tension is due to the weight or the selected posture, and also to a deliberate flexing of the muscles. The stimulation caused by the vibrations becomes optimal when it is capable of being transmitted onto the body, or onto a muscle to be treated, with a large movement component in the direction of the muscle fibers to be stimulated. In order to amplify the effect of the treatment, the treated muscles may be massaged during the treatment. For this reason, the muscle stimulation apparatus should be constructed such that the treated muscles are comfortably accessible for a massage. With the treatment of bones, the vibration should be transmitted onto the body in the direction of the bone with a movement component that is large as possible.
With a person to be treated, the vibration should be able to be transmitted at least via a contact surface for the feet and as the case may, be for the backside as well as in particular also via grips for the hands. Accordingly, the person to be treated is situated in a standing, sitting or hanging posture.
The vibration should have frequencies or periods in the region of the excitation and decay times of muscle fibers. The usual applications envisage excitation frequencies in the region of 1 to 60 Hz. Apparatus with a settable frequency permit an adaptation of the frequency to the purpose of treatment, and thus an optimal treatment. The amplitude of the vibration for example lies in the range of 1-10 mm, preferably however of 4-6 mm. The weight which may be set into vibration, lies in the range of 10-150 kg.
EP-0,929,284 describes a muscle stimulation apparatus with two foot plates which travel apart and which are pivotally mounted on a horizontally running middle axis and may be set into pivot movements via in each case one shaft each by way of an eccentric transmission. In order to avoid an undesired imbalance of the shafts, the shafts are balanced by the attachment of balancing weights. The apparatus however produces undesirably loud noises, which as air sound are transmitted directly and as body sound are emitted via the ground. The oscillations that cause the noises arise due to the inertia forces of the foot plates when pivoted up and down. These forces, which are opposite to the acceleration forces, are transmitted onto the apparatus and from this onto the ground. A further disadvantage of this apparatus lies in the fact that the foot plates, on account of their pivot movements, have the tendency to likewise displace the legs of the person standing on the plates, into a pivot movement. This pivot component of excitation must be accommodated proportionally by the ankles, the knees and the hip joints, which can lead to undesirable effects on the joints. Apparatus according to EP-0,929,284 are limited to the stimulation of the muscles in the longitudinal direction of the body and in particular to the leg muscular system. Vibrations which are to act on the muscles of the torso and the arms would have to act on the legs with undesirably large amplitudes, and be transmitted by these onto the torso on account of the damping in the ankles, knees and hip joints. This indirect excitation may lead to problems in the joints, and does not ensure a defined excitation with the torso muscles.
U.S. Pat. No. 5,500,002 describes a solution which is similar to the embodiments of EP-0,1929,284, with two foot plates which may be set into a pivot movement, wherein the foot plates may be excited with different and settable amplitudes. This solution likewise has the disadvantages described above.
U.S. Pat. No. 5,273,028 describes a solution with a parallel vibrating plate, wherein the vibration is not produced by a rotating shaft, but via electromagnetic actuators. The application is limited to the stimulation via the feet and legs. Furthermore, noise arises from the electromagnetic actuators.
A further device with electromagnetic actuators is known from U.S. Pat. No. 5,484,388. This device is employed in the field of bone treatment, wherein a bone which is preloaded with a static force is impinged with force impacts in the direction of the static force. The embodiment is constructed in a complicated manner, is cumbersome in its application, and is not directed to vibrating muscle stimulation.
U.S. Pat. No. 2,427,053 describes a device with vibrating surfaces in the region of a seat or back rest, wherein the movement is effected tangentially to the surface of the contact surfaces. Because tangential movements are already greatly dampened in the region of the skin- and fat layer close to the surface, the desired muscle stimulation cannot be achieved in a sufficient scope.
An apparatus is commercially available whose contact surface executes a forwards and backwards movement with a tilt component. Apart from the unacceptable production of sound, the tilt component of the vibration is also an undesirable disadvantage of this solution. The apparatus comprises a rod arrangement which may be fastened at the contact surface and which extends up to beyond the body surface of a person to be treated. Grips are arranged at the upper end of the rod arrangement, so that as the person grasps the grips with tensed muscles for the stimulation of the arm muscles, the amplitude of the tilt component of the vibration is increased linearly by the rod arrangement. A movement at the grips arises on account of this, which is not suitable for the desired treatment.